Teachers matter in school development is the premise of Professional Development and School Improvement, a book based on case studies from the European-funded project EUDIST (European Development of Innovative Science Teaching). The authors, from Austria, Germany, Spain, Ireland, and Sweden, present their national experiences and results from qualitative studies of educational planning in Curriculum Workshops and related science teacher professional development. In a cross-case study a European/Canadian writing team elaborates different aspects of European reform and teachers’ chances to raise their voice in this process.